Buffers

A buffer is in (logical of physical) inventory point for a item at a certain location.

Different types of buffers exist:

  • The default buffer uses an “producing” operation to replenish it with additional material.
  • An infinite buffer has an infinite supply of the material is available.

Fields

Field

Type

Description

name

non-empty string

Unique name of the buffer.
This is the key field and a required attribute.
You have to use the convention of using “item @ location” as the buffer name.

item

item

Item being stored in the buffer.
This is a required field.

location

location

Location of the buffer.
This is a required field.
The working hours and holidays for the buffer are taken from the ‘available’ calendar of the location.

description

string

Free format description.

category

string

Free format category.

subcategory

string

Free format subcategory.
If this field is set to ‘tool’, the field ‘tool’ will automatically be set to true.

onhand

double

Inventory level at the start of the time horizon.
Default is 0.

minimum

double

Desired minimum inventory, aka safety stock.
Use this field if the safety stock doesn’t change over time.
The solver treats this as a soft constraint, ie it tries to meet this inventory level but will go below the minimum level if required to meet the demand.
A problem is reported when the inventory drops below this level.The safety stock target is expressed as a quantity. If you want to define a safety stock target as a time value (aka days of inventory), you can set a post-operation timeon the producing operation of the buffer.

minimum_calendar

calendar

Refers to a calendar storing the desired minimum inventory level, aka safety stock.
Use this field when the minimum inventory level is varying over time. Otherwise use the minimum field. If both fields are specified, the minimum field is ignored.

maximum

double

Refers to a calendar storing the maximum inventory level.
This field is not used by the solver.
A problem is reported when the inventory level is higher than this limit.

maximum_calendar

calendar

Refers to a calendar storing the maximum inventory level.
Use this field when the maximum inventory level is varying over time. Otherwise use the maximum field. If both fields are specified, the maximum field is ignored.

mininterval

duration

Replenishment batching window.
When multiple replenishments for the buffer are planned closer than the time window specified in this field, the solver algorithm will try to combine them into a single larger replenishment.
The default value of the batching window is -1, which keeps the batching logic deactivated.

producing

operation

This operation will be instantiated by the solver to replenish the buffer with additional material.
You can specify this operation explicitly.
Or, you can leave this field blank and let the system automatically create an operation. The generated operation is using the ItemSupplier and ItemDistribution models as input.
In versions before 3.0 the only way was the explicit construction of the operation to populate this field. From version 3.0 onwards we recommend to use the auto-generated operations, unless you have some very specific modeling requirements.
From version 4.0 onwards, this field is deprecated. It is left only for backwards compatibility. New implementations and upgraded installs should use the easier modeling constructs itemsupplier, itemdistribution and operation.

detectproblems

boolean

Set this field to false to supress problem detection on this buffer.
Default is true.

flows

list of flow

Defines material flows consuming from or producing into this buffer.

flowplans

list of flowplan

This field is populated during an export with the plan results for this buffer. It shows the complete inventory profile.
The field is export-only.
The description of the flowplan model is included in the section on operationplan.

tool

boolean

A flag to mark buffers that are actually representing a tool.
Default is false.
The impact on the planning results is visible in the pegging and criticality calculations.

level

integer

Indication of how upstream/downstream this entity is situated in the supply chain.
Lower numbers indicate the entity is close to the end item, while a high number will be shown for components nested deep in a bill of material.
The field is export-only.

cluster

integer

The network of entities can be partitioned in completely independent parts. This field gives the index for the partition this entity belongs to.
The field is export-only.

hidden

boolean

Marks entities that are considered hidden and are normally not shown to the end user.

Buffer_default

The default buffer uses an “producing” operation to replenish it. No fields are defined in addition to the ones listed above.

Buffer_infinite

An infinite buffer has an infinite supply of the material is available.

The PRODUCING field is unused for this buffer type.

Propagation through a bill of material will be stopped at an infinite buffer.